High streets in Sydney should declare recurring car-free days when pedestrians and cyclists can roam freely and local shops and restaurants can sprawl out to allow a street festival culture to flourish, an influential thinktank says.

The Committee for Sydney and the Sydney festival executive director, Chris Tooher, are appealing to the New South Wales government and councils to mimic cities such as New York, Jakarta, Mexico City and Bogotá in making so-called open street days established events, such as every Sunday.